Cereal products are popular food items especially Ready-To-Eat ("R-T-E") breakfast cereals and snack products. Preparation of finished cereal products generally involves, at some point during manufacture, the preparation of cereal pellets from a cooked cereal dough or further processing of pieces of cooked cereal materials.
For example, in the preparation of unpuffed R-T-E cereals, cereal pellets are formed and the pellets are then flaked, shredded or otherwise shaped prior to toasting, baking or other finishing steps. In the preparation of puffed R-T-E cereals, cereal pellets are formed, dried and then gun puffed or fluid bed puffed with hot air. Cereal based snack products are generally similarly processed except that the unpuffed cereal pellets are puffed or expanded by deep fat frying. In the production of a shredded wheat R-T-E cereal, cooked whole wheat berries are shredded and formed into biscuits prior to finish baking.
The term "half product" is sometimes used equivalently in the art to the term cereal pellets but more frequently connotes an unpuffed piece to be puffed by deep fat frying to form a puffed snack. While R-T-E cereal pellets and snack half products have differences, each generally are fabricated from farinaceous cooked cereal doughs. Cereal pellets are generally smaller in size and often comprise higher amounts of sucrose while snack half products are generally larger and have little or no sucrose.
During the course of fabrication of cereal pellets or snack half products, a common unit operation is tempering. The term "tempering" in a snack or breakfast cereal process denotes a unit operation different from the operation with the same name in other food processing processes, e.g., flour milling. In a snack or breakfast cereal process "tempering" usually follows a drying or cooling step and is the step of holding the pellets for an extended time period which allows the cooked grain mass or cereal pellets to equilibrate moisture within and among the particles. Proper moisture equilibration can be important to a wide variety of intermediate product or final product properties.
Tempering, for example, may be important to the flakability or shreddability of pellets in cereal piece shaping or other fabrication. Tempering can also be important to the puff volume of finished pieces or to the uniformity or evenness of puff. In other applications, tempering can be important to providing improved bowl life.
Tempering traditionally involved holding the pieces (pellets, cooked grain grits, snack half products, etc.) such as in a temper bin or on a belt for periods of up to 24 hours. With modern controlled-humidity dryers, tempering times can generally be reduced to a matter of hours. Unfortunately, these still relatively lengthy temper times require substantial capital investment in holding equipment and reduce manufacturing flexibility. While improvements in cereal processing have substantially reduced the time, expense and inconvenience of tempering, there is a continuing need for new and useful improvements in cereal processing to provide methods for moisture equilibration of cooked cereal pieces.
Still another problem in the cereal processing art involves, in particular, the preparation of puffed cereal products. Certain puffed R-T-E cereal products upon gun puffing exhibit defects in the homogeneity of body of the puffed cereal piece. For example, in the preparation of certain corn based spherical R-T-E cereal products, a significant percentage of the puffed cereal base may undesirably exhibit large voids or even hollow cores. These defects not only are visually undesirable but also adversely affect texture and bowl life. Increasing temper times prior to puffing can improve the puff properties of the finished product but increase the cost of preparation as well as create a throughput bottleneck in continuous cereal product manufacturing. In view of these deficiencies in the cereal processing art, it is an object of the present invention to provide new and better microwave tempering steps.
Another object of the present invention is to provide improved methods for tempering cereal pellets which reduce the need for lengthy temper holding times and the need for expensive temper holding equipment.
Another object of the present invention is to provide methods for tempering cereal pellets which are useful in the manufacture of a large variety of ready-to-eat cereal and cereal based snack products.
Still another object of the present invention is to provide methods for tempering cereal pellets which can be practiced with present cereal and snack product methods and facilities.
Still another object of the present invention is to provide tempering methods which improve the throughput of existing cereal and snack half product production facilities.
Another object of the present invention is to provide improved tempering methods for cereal pellet and snack half product processing which improves the expanded finished product properties.
Surprisingly, the above objectives can be realized and the present invention provides improvements to known cooked cereal processing methods. More specifically, the present invention provides improvements in the tempering of cooked cereal pieces by briefly exposing the piece to high intensity microwave fields.